The present invention relates to an electric control trigger assembly for staple guns and can be controlled by three molds.
A conventional staple gun is shown in FIG. 1 and generally includes a handle 1 with a main passage 11 which is connected to a source of air from a compressor (not shown) and a barrel is connected to the handle 1 with a chamber 10 defined in the barrel. A cylinder 24 is received in the barrel 10 and an end mount assembly 2 is connected to a rear end of the barrel and a nose is connected to a front end of the barrel. An end cap 22 is movably connected to an inside of the end mount assembly 2 and biased by a spring 22 so as to seal an open end of the cylinder 24 in which a piston 25 is movably received in the cylinder 24. A magazine for receiving staples is connected to the nose. A recess 12 is defined in a wall of the handle 1 and a trigger valve 4 is received in the recess and can be activated by a trigger 5. Pressurized air may enter the recess 12 via a gap between the valve 4 and the opening in the wall of the handle 1 and enters a tube 3 engaged with a hole 14 defined in an inside of the handle 1 and a path 20. The pressurized air enters a space between the end cap 22 and the end mount assembly 2 via the path 20 so that the opening of the cylinder 24 sealed by the end cap 22 by the pressure in the space and the spring 21.
When a safety plate 55 is pushed toward the trigger 5 and the trigger 5 is squeezed the shaft of the trigger valve 4 is shifted to seal the opening communicating with the recess 12 and the pressure in the space mentioned above is reduced so that the end cap 22 is pushed toward the end mount assembly 2 by the pressure in the main passage 1. Once the end cap 22 is moved to open the open end of the cylinder 24, the piston 25 is moved to eject a staple by a plate connected to the piston 25 from the nose. Air in the cylinder 24 is pushed out via orifices defined through the wall of the cylinder 24 into the chamber 10. After shooting, the trigger 5 is released and the air in the chamber 10 enters the cylinder 24 again to push the piston 25 back to its original position. Simultaneously, air in the main passage 11 enters the tube 3 and the path 20 to assist the spring 21 to move the end cap 22 to seal the open end of the cylinder 24 again.
If the users want to have a continuous firing action, the trigger 5 has to be pressed all the time and then remove the safety plate 55 to the next object and press the safety plate 55 to shoot another staple. This could mis-fire the staple when the safety plate is unintentionally pushed.
The safety plate 55 and the trigger 5 are exposed and protrude from the barrel of the staple gun so that they could be tangled by other object or activated unintentionally.
The present invention intends to provide a staple gun wherein the trigger assembly is controlled by electric way so that the staple gun can be used in a continuously firing mold precisely.
In accordance with one aspect of the present invention, there is provided a staple gun which comprises a barrel with a chamber defined therein and a piston is movably received in a cylinder received in the chamber. A plate is connected to the piston and extends through a nose connected to a front end of the barrel. An end mount assembly is connected to a rear end of the barrel and an end cap movably seals an open end of the cylinder. A spring is biased between the end cap and an inside of the end mount assembly. A sensor is connected to a distal end of the nose and activated by a movement of a safety member movably mounted to the nose.
A handle is connected to the barrel and a main passage is defined in the handle. She main passage communicates with the chamber in the barrel and an opening is defined through a wall of the handle and communicates with a recess in the handle. An electro-magnetic valve is engaged with the recess and has a shaft which is movable to seal the opening. A circuit board is connected to the handle and electrically connected to the sensor and the electro-magnetic valve, wherein the circuit board, the sensor, and the electro-magnetic valve forms a circuit to control the movement of the shaft to seal the opening.
A button switch, a mold switch, an adjusting pulse switch and a battery set are connected to the circuit board. The mold switch activates various independent circuits and controls a number of reciprocating movement of the shaft of the electro-magnetic valve.